At present, diverse processes are known to obtain products with spores of mycorrhizal fungi, for example, that described in document DE3932746 (A1). This document describes a material of support with dibasic mineral wool for the production and application of vesicular-arbuscular mycorrhizal fungi. This material of support has many advantages in comparison with the expanded clay, but this document does not mention nor anticipates the process described in the present invention. In addition the composition in the form of pelletized granules with spores of endomycorrhizal fungi covered with mineral clays of the present invention is not mentioned nor suggested. In addition, CA 1270454 (A1), describes a process to prepare a composition of inoculant support to inoculate a plant of vesicular-arbuscular mycorrhizal fungi, the process comprise to deal an adsorbent particle with internal surfaces greater than the outer surfaces, with roots of the plant infected with vesicular-arbuscular mycorrhizal fungi during at least two weeks to give a yield by roots that contain adsorbent particles in association with the fungi. The porous material is selected of expanded clay, pumice stone and polystyrene, in addition the adsorbent particles include an inflatable material of secondary clay, in combination with more of 50% in weight of a diluent and in combination with more of 50% in weight of sand, earth or humus, but this document does not mention nor anticipates the process and the composition described in the present invention. In the document U.S. 2008/0064598 A1, it described preparations of mycorrhizal fungi that form arbuscules, to obtain these preparations an inoculant is cultivated in porous granulating and the crude inoculant that is produced is ground in such a way that active spores are not destroyed. Porous granules as substrate are of expanded clay or atapulgite or expanded slate or volcanic rock or pearlite or vermiculite or mixtures of two or more of these materials, but this document either mentions and neither anticipates the process and composition described in the present invention. The present invention is considered by the inventors to be new and inventive and is not suggested or anticipated by documents before mentioned.
In order to study mineral particles of a ground, the scientists classify them regulating in advisable groups according to its size. These different groups are called fractions, separatas or separated. The analytical procedure by which the particles are thus separated calls mechanical or grain sized analysis. It is really a determination of the distribution of the particle sizes. According to the System of the Department of Agriculture of the United States and the International System of the Sciences of the Ground, the classification of grounds is mentioned in the following way (Table 1):
TABLE 1Classification of particles of the ground accordingto two systems (U.S.A and International)System of theInternationalDepartment ofSystem of theAgriculture of theScience of theUnited StatesagroundbFraction of theDiameters limitsDiameters limitsgroundin mmin mmVery heavy sand2.00-1.00Heavy sand1.00-0.502.00-0.20Medium sand0.50-0.25Fine sand0.25-0.100.20-0.02Very fine sand0.10-0.05 0.02-0.002Slimes 0.05-0.002ClayLess than 0.002Less than 0.002
So that a ground is to be designated as a clay it must have, like minimum, a 35% of argillaceous fraction. The clay exists in the call colloidal state, in which their individual particles are characterized by their extraordinarily small size, great area of dispersion by mass unit and the presence, in surface, of electrical charges to which the water molecules feel attracted so much as ions.
The clay particles commonly are prepared in plates or grudges, like mica, and if they become damp are very plastic. When the clay with a suitable amount of water gets wet, it dilates and it becomes sticky. When it dries it shrinks with the adsorption of considerable energy. Becoming damp again, it appears the swelling, with change of temperature. The absorbent capacity of clays for water, gases and solubles salts are very high.
It recognizes three types of important minerals, although others are known in significant quantities, kaolinite, illite and montmorillonite. These groups greatly vary in plasticity, cohesion and adsorption, being the kaolinite the lowest in these properties and montmorillonite the highest.
Chemically the kaolinite and the other members of this special group are aluminic silicates. The same happens to the montmotillonita and other clays of the same type of crystallization, but these take in addition sodium, iron or magnesium, according to the cases.
A bentonite is a compound rock essentially by minerals of the group of the smectites. The criteria of classification used by the industry are based on their behavior and physic-chemical properties; thus the more accepted industrial classification establishes three types of bentonites based on its capacity of swelling in water:
Bentonite highly inflatable or sodics
Bentonites little inflatable or calcics
Bentonites moderately inflatable or intermediate.
Physic-Chemical Properties of Clays
The physic-chemical properties of clays derive, mainly of:
Its extremely small sizes of particle (inferior than 2 μm)
Its laminar morphology (filosilicates)
The isomorphic substitutions, that cause the appearance of load in laminae and to the cation presence weakly related in the interlaminar space.
As a result of these factors, they present, on the one hand, a high value of superficial area and, simultaneously, the presence of a great amount of active surface, with unsaturated bonds. For that reason they can interact with very diverse substances, in especially compounds polar, reason why they have plastic behavior in mixtures clay-water with high proportion solid-liquid.
The high plasticity of clays is consequence, again, of its laminar morphology, extremely small particle size (high superficial area) and high swelling capacity. In general so more small are the particles and more imperfect its structure, the material is more plastic.
Fertility
It recognizes six external factors that influence in the life of the plants: light, mechanical support, temperature, air, water, and nutrients. Except the light, the ground is an agent of supplying of all these factors. The capacity of grounds to supply some essential elements to the plants superiors is a fundamental problem in the production of harvests. In order to obtain that the secondary nutrients and micronutrients that are applied to the ground through use of fertilizer do not react forming compound that prevents their assimilation, it is necessary that they are in grounds where a high capacity of cationic exchange exists. This is not always possible and sometimes when they are applied they arrive in very small amounts or they absolutely do not arrive at the plant to react and to become on non assimilable compound. This brings consequently that it must use high amounts of fertilizer being few economic and for long time can get to be toxic for the ground besides causing to its eutrophycation and the contamination of water bodies.
In the last decades it has been tried to change in the global scope the paradigms of the agricultural production that implied the intensive use of energy, machinery and chemical substances, by a new concept, the one of viable agriculture. According to this new concept viable agriculture must:                a) To satisfy the human needs of fiber and foods.        b) To improve the environmental quality and the base of natural resources on which the agricultural economy depends.        c) To make an efficient use of the nonrenewable resources.        d) To maintain the economic viability of the agricultural activities and        e) To increase the quality of life of the agriculturists and the society like a whole.        
In agreement with these needs the use of biofertilizers, that is to say, products of natural occurrence, whose active ingredient are spores or vegetative cells of microorganisms, or extracts of plants; it is a useful tool to approach us to an viable agriculture.
An example of this type of product are the mycorrhizas, that are beneficial associations that settle down between some fungi of the ground and the roots of vascular plants.
The mycorrhizas improve the growth of the plant with the increase of the surface of absorption of the radicular system; with the selective absorption and with the accumulation of certain nutrients, especially phosphorus; with the solubilization and dispose some minerals normally insoluble, allowing that the nourishing roots work during more time; and causing that the nourishing roots been more resistant to the infection that cause some pathogenic fungi to the ground such as Phytophthora, Pythium and Fusarium. 
In the literature it appears reported the tendency of the endomycorrhizal fungi to spore within others spores of endomycorrhizal fungi suggesting that dead spores provide of a favorable microhabitat for the formation of spores. Also one has reported a greater sporulation of endomycorrhizal fungi within rest of insects, dead seeds and seminal covers, which has been interpreted like a mechanism that would favor the survival of the set out spores to adverse environmental conditions. This fact has been made by some authors for the use of expanded clay in the production of commercial inoculant, since that spores proliferates within the cavities produced by clays.
At present there exist several inoculant products made with endomycorrhizal fungi like dust whose application is traditionally direct to the seed. In this type of products like dust, the endomycorrhizal fungi are totally set out to the environmental conditions and the mechanical damage during the handling of the product, suffering structural rupture or even their death, which considerably decreases the effectiveness of the product. At being exhibited the structures of the endomycorrhizal fungi exists the risk of they enter in direct contact with some product fungicide that has also been applied to the seed causing its death. Under this same context, the fungi are susceptible to be parasitized by some injurious agent preventing their installation in the root of the plants and/or causing their death. In these dust products also exists the possibility of death of the endomycorrhizal fungi by drastic and continuous changes of temperature, the spores tends to undergo dehydration. Besides the above mentioned, the use of adherents is generally rigorous so that the dust product can fix to the seed, which makes more expensive the application, this work requires of enough time and manpower. Sometimes the dust disperses in water for its application to the ground, nevertheless, this dust is not soluble in the water and far from to optimize the application it returns inefficient so that the dust settles within the application equipment and covers the holder of the seeding machines that are used, causing that the packings wear out, the adjustment of the equipment is very expensive and it loses long time and product. By the nature of these dust products, its application in mixture with granulated fertilizers would be inefficient since a good homogenization due to the difference in the particle size is not obtained.